1. Field of the Invention
This invention is in the field of angiography using a liquid contrast dye.
2. Background Information
A procedure commonly performed is the catheterization of the cardiovascular system of a patient, requiring the performance of angiography to assist the physician in visualizing the catheter and other instruments within the blood vessels. Typical of procedures for which catheterization is performed are atherectomy and angioplasty procedures. During angiography, a radiopaque contrast dye or other medium is usually injected into the vascular system to render the lumen of the vessel visible via radiographic equipment.
The contrast dye is typically provided in containers such as bottles with puncturable receptacles. The receptacle is punctured with a spike, which can be vented, and the spike is typically connected to the proximal end of a flexible tube. The bottle is hung from a stand to provide a hydrostatic head, and the distal end of the flexible tube can be connected to a manifold or other valving device. The manifold is also connected to a syringe and to the proximal end of a guide catheter, the distal end of which is inserted into the vascular system of the patient.
During the catheterization procedure, when the physician wishes to inject dye into the blood vessel, the plunger of the syringe is first withdrawn, with the manifold or other valves aligned as required to allow flow of dye from the contrast bottle, through the tubing and the manifold, to the syringe. The manifold valves are then realigned as necessary, to allow flow from the syringe to the guide catheter, and the plunger is pushed into the syringe to dispense contrast dye into the patient's vascular system, through the manifold and the guide catheter. After the syringe is emptied, if another dye injection is required, the physician again draws dye from the bottle into the syringe and dispenses the dye into the guide catheter.
Two problems can result from this conventional method of dye injection. First, the method is unnecessarily expensive, because it wastes large amounts of very expensive contrast dye. Each cardiovascular catheterization procedure typically only requires about 70 or 80 milliliters of contrast dye. After performance of the typical procedure, some of the contrast dye usually will be left in the bottle. This remaining dye can not be used in a subsequent procedure on another patient, because of the risk of contamination. In other words, contaminated fluids from the first patient might conceivably flow back through the syringe to the contrast bottle, subsequently contaminating the second patient. To guard against this possibility, the contrast dye remaining in a bottle typically is discarded. If large bottles are used, a large amount of dye can be wasted. Considering that the contrast material costs approximately one dollar per milliliter, this practice results in substantial unnecessary expense.
Secondly, when the physician repeatedly fills the syringe, if the contrast bottle approaches empty, air will eventually be drawn into the tubing and possibly into the syringe. This requires stopping the catheterization procedure while a new bottle of fluid is attached, and while the air is purged from the syringe and the tubing. If smaller bottles are used to limit waste, additional time in surgery can be required for repeatedly changing bottles and repriming the flowpath. Given the invasive nature of cardiac catheterization in particular, and given the fact that blood flow in the affected vessel is substantially reduced during the procedure, any delay in the procedure is very undesirable.
It is an object of the present invention, then, to provide a method and apparatus for injecting radiographic dye into a vascular system, which will allow the use of essentially all of the contrast material in a bottle before discarding the bottle, without fear of contamination. It is a further object of the present invention to provide a method and apparatus for injecting radiographic dye into a vascular system, which will allow the replacement of an empty contrast bottle with a replacement bottle, without stopping the procedure. Finally, it is an object of the present invention to provide a method and apparatus for injecting radiographic dye into a vascular system, which is easy and economical to implement.